On March 1, Collider Run II
began at Fermilab. It is a six-year
enterprise to produce a record
number of proton-antiproton
collisions using the world's most
powerful particle accelerator, the
"This machine doesn't have an
on/off switch," said Mike
Martens, who just assumed the
responsibility as Run II
coordinator. "Every time we start a run, we have to tune the
machines, slowly increasing the luminosity."
Luminosity is expert's lingo for the number of collisions produced per
second. So far, Fermilab accelerator experts have achieved a peak
rate of about 450,000 collisions per second (a luminosity of
7.5x1030 cm-2sec-1), a respectable start for Run II. By January,
they want to increase the luminosity to 4x1031 ("four times ten to the
thirty-one"), improving the previous record obtained during Run I,
which ended in 1996, by about a factor of two.
At present, scientists are using a six-week shutdown to improve
accelerator operations and to put the final touches on the CDF and
DZero detectors, large instruments that take "snapshots" of the
collisions, revealing the nature of the tiniest building blocks of matter.
In the past seven months, both CDF and DZero collaborations have
tested their equipment, collected the first collision data and refined
their computer controls. The planned shutdown, which began on
October 8, gives them a chance to repair equipment and supplement
existing electronics before the recording of "real" data will start
The Department of Energy's Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time.